The overall goal of these studies is to explore the interactions of the human immune system and local factors with specific group A streptococcal antigens or mitogens as these interactions may play a role in the development of rheumatic fever and rheumatic heart disease. The study will be conducted from several foci: a) the purification and characterization of a panel of streptococcal extracellular products and cellular components and the definition of their interaction with lymphocytes, b) a comparison of the response of peripheral and tonsillar lymphocytes to these well-characterized group A streptococcal substances (antigens or mitogens) in rheumatic and control patients, c) an examination of other local factors heart disease, d) correlation of these immunologic bacteriologic and chemical factors in rheumatic and non-rheumatic patients.